ASoC: wcd9320: Add ANC loopback path and cache HPF bypass control

Add route to connect ANC FB tune signal back to decimator
DEC7 to DEC10. These paths are used to evalute the device acoustics
and provide a way to tune ANC algorithm. In addition, a logic is
implemented to cache the TX HPF bypass control to allow user
bypass the TX HPF during ANC tuning.

Change-Id: Id6b8a046480fcfb5a4d0fb1876f7c364796d4378
Signed-off-by: Jay Wang <jaywang@codeaurora.org>